BACKGROUND: A standard phenotype of frailty was associated with an increased risk of adverse outcomes including mortality in a recent study of older adults. However, the predictive validity of this phenotype for fracture outcomes and across risk subgroups is uncertain. METHODS: To determine whether a standard frailty phenotype was independently associated with risk of adverse health outcomes in older women and to evaluate the consistency of associations across risk subgroups defined by age and body mass index (BMI), we ascertained frailty status in a cohort of 6724 women>or=69 years and followed them prospectively for incident falls, fractures, and mortality. Frailty was defined by the presence of three or more of the following criteria: unintentional weight loss, weakness, self-reported poor energy, slow walking speed, and low physical activity. Incident recurrent falls were defined as at least two falls during the subsequent year. Incident fractures (confirmed with x-ray reports), including hip fractures, and deaths were ascertained during an average of 9 years of follow-up. RESULTS: After controlling for multiple confounders such as age, health status, medical conditions, functional status, depressive symptoms, cognitive function, and bone mineral density, frail women were subsequently at increased risk of recurrent falls (multivariate odds ratio=1.38, 95% confidence interval [CI], 1.02-1.88), hip fracture (multivariate hazards ratio [MHR]=1.40, 95% CI, 1.03-1.90), any nonspine fracture (MHR=1.25, 95% CI, 1.05-1.49), and death (MHR=1.82, 95% CI, 1.56-2.13). The associations between frailty and these outcomes persisted among women>or=80 years. In addition, associations between frailty and an increased risk of falls, fracture, and mortality were consistently observed across categories of BMI, including BMI>or=30 kg/m2. CONCLUSION: Frailty is an independent predictor of adverse health outcomes in older women, including very elderly women and older obese women.